Java netty MessagePack编解码（粘包/拆包支持）

EchoServer:

package messagepack;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;

/**
 * 时间服务器，当有客户端请求时，返回服务端当前时间
 */

public class EchoServer {

    public void bind(int port){

        //NioEventLoopGroup是一个线程组，它包含了一组NIO线程，
        // 这里的两个线程组一个是用于服务端接受客户端的连接，
        // 另一个用于SocketChannel的网络读写
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            //netty用于启动NIO服务端的辅助启动类
            ServerBootstrap b = new ServerBootstrap();

            //设置线程组
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)//设置channel
                    .option(ChannelOption.SO_BACKLOG, 100)//设置channel的TCP参数
                    .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000)
                    .childHandler(new ChildChannelHandler());//绑定IO事件处理类

            //绑定监听端口，调用同步阻塞方法等待绑定完成
            ChannelFuture f = b.bind(port).sync();
            //阻塞，等待服务端链路关闭后main函数才退出
            f.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            //优雅退出，释放跟shutdownGracefully相关联的所有资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    private class ChildChannelHandler extends ChannelInitializer<SocketChannel>{

        @Override
        protected void initChannel(SocketChannel serverSocket) throws Exception {
            serverSocket.pipeline().addLast("frameDecode",
                    new LengthFieldBasedFrameDecoder(65535, 0, 2,0,2));
            serverSocket.pipeline().addLast("msgpack decoder", new MsgpackDecoder());
            serverSocket.pipeline().addLast("frameEncode", new LengthFieldPrepender(2));
            serverSocket.pipeline().addLast("msgpack encoder", new MsgpackEncoder());
        serverSocket.pipeline().addLast(new EchoServerHandler());
        }
    }

    public static void main(String[] args) {
        int port = 8080;
        new EchoServer().bind(port);
    }
}

EchoServerHandler

package messagepack;


import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

import java.util.List;


/**
 * 对网络事件进行读写操作
 */
public class EchoServerHandler extends ChannelHandlerAdapter {

    /**
     * 当异常发生时
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        //super.exceptionCaught(ctx, cause);
        ctx.close();
    }

    /**
     * 读取缓冲区里面的数据，处理并返回
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        List<UserInfo> userInfo = (List<UserInfo>) msg;
      System.out.println("server receive message from client =" + userInfo);
      ctx.writeAndFlush(userInfo);
    }

}

解码器MsgpackDecoder：

package messagepack;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;
import org.msgpack.MessagePack;

import java.util.List;

public class MsgpackDecoder extends MessageToMessageDecoder<ByteBuf> {
    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List<Object> out) throws Exception {
        //首先获取需要解码的byte数组
        final byte [] array;
        final int length = msg.readableBytes();
         array = new byte[length];
        msg.getBytes(msg.readerIndex(), array, 0, length);
        //mp的read方法将其反序列化为object对象
        MessagePack mp =  new MessagePack();
        mp.register(UserInfo.class);
        out.add(mp.read(array));
    }
}

编码器MsgpackEncoder

package messagepack;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import org.msgpack.MessagePack;

public class MsgpackEncoder extends MessageToByteEncoder<Object> {
    @Override
    protected void encode(ChannelHandlerContext ctx, Object msg, ByteBuf out) throws Exception {
        MessagePack mp =  new MessagePack();
        byte [] raw = mp.write(msg);
        out.writeBytes(raw);
    }
}

传输对象UserInfo:

package messagepack;


import org.msgpack.annotation.Message;

@Message
public class UserInfo{

  private String name;

  private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "UserInfo{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

EchoClient:

package messagepack;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;

/**
 * netty的客户端
 */

public class EchoClient {

    private final String host;

    private final int port;

    private final int sendNum;

    private EchoClient(String host, int port, int sendNum){
        this.host = host;
        this.port = port;
        this.sendNum = sendNum;
    }

    public void run(){

        //NioEventLoopGroup是一个线程组，它包含了一组NIO线程
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            //客户端辅助启动类
            Bootstrap b = new Bootstrap();

            //设置线程组
            b.group(group)
                    .channel(NioSocketChannel.class)//设置Channel
                    .option(ChannelOption.TCP_NODELAY, true)//设置TCP的参数
                    .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000)
                    .handler(new ChannelInitializer<SocketChannel>() {//匿名内部类设置handler
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //解决拆包、粘包读写问题
                            //在解码器之前增加LengthFieldBasedFrameDecoder，用于处理半包消息，这样接受到的永远是整包消息
                            //个人觉得和分隔符的意义差不多
                            socketChannel.pipeline().addLast("frameDecode",
                                    new LengthFieldBasedFrameDecoder(65535, 0, 2,0,2));
                            //解码
                            socketChannel.pipeline().addLast("msgpack decoder", new MsgpackDecoder());
                            //在编码器之前增加2个消息的消息长度字段
                            socketChannel.pipeline().addLast("frameEncode", new LengthFieldPrepender(2));
                            socketChannel.pipeline().addLast("msgpack encoder", new MsgpackEncoder());
                            socketChannel.pipeline().addLast(new EchoClientHandler(sendNum));
                        }
                    });
            //异步连接客户端，同步阻塞直到连接成功
        ChannelFuture f = b.connect(host, port).sync();
            //阻塞，等待客户端链路关闭后main函数才退出
        f.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) {
        String host = "127.0.0.1";
        int port = 8080;
        new EchoClient(host, port, 10).run();
    }
}

EchoClientHandler:

package messagepack;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

public class EchoClientHandler extends ChannelHandlerAdapter {


    private final int sendNum;

     public EchoClientHandler(int sendNum){
         this.sendNum = sendNum;
     }


    /**
     * 连接服务端成功后开始发送消息
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
     UserInfo [] userInfos = userInfo();
        for (UserInfo userInfo: userInfos) {
            ctx.writeAndFlush(userInfo);
        }
       // ctx.writeAndFlush(userInfos[0]);
    }

    private UserInfo [] userInfo(){
        UserInfo [] userInfos = new UserInfo[sendNum];
        for (int i = 0; i < sendNum; i++){
            UserInfo userInfo = new UserInfo();
            userInfo.setAge(i);
            userInfo.setName("ABCDEF------->" + i);
            userInfos[i] = userInfo;
        }
        return userInfos;
    }

    /**
     * 读取客户端的返回消息
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Client receive the msgpack messag:" + msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }

    /**
     * 发生异常时关闭ctx
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        //super.exceptionCaught(ctx, cause);
        ctx.close();
    }
}

Java netty MessagePack编解码（粘包/拆包支持）

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